ClinicalTrials.gov: 2023 URI update and ctgov prefix (#897)

refs greenelab/covid19-review#1210

Two changes (one per commit) that should be treated as separate (I can
remove either of the changes from this PR based on review).

src/bioregistry/data/bioregistry.json

@@ -14910,8 +14910,10 @@
     ],
     "synonyms": [
       "NCT",
-      "clinicaltrial"
+      "clinicaltrial",
+      "ctgov"
     ],
+    "uri_format": "https://www.clinicaltrials.gov/study/$1",
     "wikidata": {
       "database": "Q5133746",
       "description": "identifier in the ClinicalTrials.gov database",